JP2009-154338A (Patent Document 1), JP2009-250364A (Patent Document 2), and JP2011-152729A (Patent Document 3) disclose a method of manufacturing a resin rotator, in which a reinforcement fiber substrate (molding material) is formed on the outer peripheral portion of a bushing using slurry obtained by mixing reinforcement fibers formed of short fibers and a dispersion medium such as water. In the methods described in the documents mentioned above, the slurry is poured into a cylindrical die that houses a metal bushing, water is removed from the slurry through a bottom member that has a filtration function such that reinforcement fibers will not leak out but be aggregated around the bushing to form an aggregate, and then the aggregate is compressed to form a reinforcement fiber substrate (molding material). A mold device provided with a molding die including at least a cylindrical die having an opening portion opened in an upward direction, and a lower compression mold and an upper compression mold, both of which are disposed inside the cylindrical die during molding, is used to compress the aggregate.